JP2022131607A - Terminal-equipped wire, wire harness, manufacturing method of terminal-equipped wire - Google Patents

Abstract

To provide a terminal-equipped wire or the like capable of achieving both connection strength and connection resistance.SOLUTION: A terminal-equipped wire 10 is configured by electrically connecting a terminal 1 and a covered conductor 11. A conductor has a cross-sectional area of 0.3 sq or less and is crimped by a conductor crimping portion 7. The conductor crimping portion 7 of the terminal 1 is formed into a substantially tubular shape by rolling the ends of a flat plate-shaped material such that the ends thereof meet, and welding at least a part of the butting portion, and a weld bead 23 is formed at the welded butting portion. Here, it is desirable that the area of the weld bead 23 of the butting portion on the inner surface of the conductor crimping portion 7 is 20% or less of the total inner surface area of the conductor crimping portion 7.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a terminal-equipped electric wire and the like used in automobiles and the like.

Generally, wire harnesses for automobiles are bundled after crimp terminals are connected to the conductors of coated wires, and routed as signal wires for automobiles and the like. A general coated conductor and a crimp terminal are connected by removing the coating of the tip of the coated conductor, crimping the exposed conductor and the conductor crimping part, and crimping the covering part by the crimping part. At this time, although an oxide film with poor conductivity is formed on the surface of the conductor, this oxide film can be destroyed by applying strong compression when crimping the conductor wire crimping portion. For this reason, the element wire constituting the conductor is brought into contact with the conductor crimping portion of the crimp terminal to obtain electrical continuity with the crimp terminal.

However, especially in wire harnesses used in automobiles, wires thinner than conventional wires are sometimes used to reduce weight, and wires with a diameter of 0.3 sq (sq: ^mm2 ) or less are required. there is As described above, in the case of a thin electric wire, there is a problem that the tensile strength of the connecting portion is remarkably lowered due to breakage of the wire due to excessive compression or damage to the wire. However, if the compression is weakened, as described above, the oxide film is not sufficiently destroyed, and there is the problem of increased resistance at the connection.

That is, strong compression causes damage to the wire and tends to reduce the strength of the crimped portion, while weak compression does not sufficiently destroy the oxide film, increases the resistance of the crimped portion, and results in insufficient crimping. Therefore, the strength of the crimped portion cannot be ensured because of the pull-out. As described above, it is difficult to control the balance between conductivity and tensile strength only by compressibility, especially in a small-diameter coated wire. For this reason, there is a demand for a connection body in which the balance between conductivity and tensile strength can be easily controlled by compressibility in one press-fitting.

On the other hand, an electric wire containing a tensile strength member is being considered. For example, when using an electric wire made of a conductor with a tensile strength of about 30 N, in order to ensure a tensile strength exceeding 80 N required for electric wires for automobiles, a wire containing a tensile strength member made of metal or non-metal It has been proposed that a conductive wire is spirally wound around the outer circumference of a tensile strength member. Such an electric wire is prepared by stripping the conductor, exposing the tensile strength member, inserting it into a sleeve, crimping the tensile strength member with a steel clamp, integrating it with a hardening resin such as an adhesive, and removing the conductor. There is a method of crimping with a clamp made of aluminum or the like (Patent Document 1).

In addition, a conductor part formed by bundling a plurality of strands, and a coating in which a fibrous tensile member is arranged in a valley existing between the strands on the outer peripheral side of the conductor part and the inner peripheral side of the coating material An electric wire has been proposed (Patent Document 2).

Japanese Utility Model Laid-Open No. 61-046827 JP 2012-3856 A

However, in both Patent Document 1 and Patent Document 2, for example, when connecting to a crimp terminal using a large-diameter covered conductor, the crimping at the conductor crimping portion is performed at a compression rate that achieves both connection strength and connection resistance. However, as the diameter of the wire becomes thinner, the range of suitable crimping conditions for both connection strength and electrical resistance becomes narrower. This is because, as mentioned above, if you try to secure the connection strength, the conductor will break and the connection resistance will increase. be. Thus, as the wire diameter becomes thinner, it becomes more difficult to achieve both connection strength and electrical resistance.

For example, in Patent Document 1, if the compression ratio during crimping is low (that is, strong compression), the tensile strength is reduced due to damage to the tensile strength body, and if the compression ratio during crimping is high (that is, low compression), the crimped portion resistance increases. In addition, when connecting a conventional electric wire containing a tensile strength member, it is necessary to carry out step stripping work and crimping processes for crimping the tensile strength member and crimping the conductive wire respectively. Therefore, the number of parts is large, the number of work steps is also increased, and the cost is high. In particular, when the diameter of the electric wire becomes small, step stripping itself becomes difficult. Thus, in Patent Document 1, the manufacturing process becomes complicated, so there is a problem that the processing cost increases.

Further, Patent Document 2 discloses an example in which strength is improved without degrading electrical properties by providing a fibrous tensile member between conducting wires. However, in Patent Document 2, similarly to Patent Document 1, if the compression ratio during crimping is low, the tensile strength is reduced due to damage to the tensile member, and if the compression ratio during crimping is high, the resistance of the crimped portion increases. the issue has not been resolved.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to provide a terminal-equipped electric wire or the like capable of achieving both connection strength and connection resistance.

In order to achieve the above object, a first invention is an electric wire with a terminal in which a coated conductor and a terminal are electrically connected, wherein the coated conductor comprises a tensile strength member, a conductor, and the tensile strength member and the conductor. The conductor wire has a cross-sectional area of 0.3 sq or less, and the terminal includes a conductor crimping portion to which the conductor exposed from the covering portion at the tip of the covered conductor wire is crimped; and a coated crimping portion to which the coated portion of the coated conductor is crimped, wherein the conductor crimping portion is formed by rounding the end portions of a flat plate-shaped material so that the ends thereof are butted against each other, and at least a portion of the butt portion is welded. The area of the weld bead of the butt portion on the inner surface of the conductor crimping portion is 20% or less of the total inner surface area of the conductor crimping portion, and the conductor is formed in the conductor crimping portion, The electric wire with a terminal is characterized in that the electric wire is crimped from the entire circumferential direction of the conducting wire.

It is desirable that the plate thickness of the terminal is 0.3 mm or less.

It is desirable that the compressibility of the wire crimping portion is 55% or less.

The tensile strength member may consist of a plurality of wires.

The conductor wire may be twisted around the outer circumference of the tensile strength member.

At least the tip portion of the conducting wire may be compressed from the outer peripheral side.

The conductive wire may be plated.

It is desirable that the conductor crimping portion does not come into contact with the tensile member.

According to the first aspect of the invention, the conductor crimping portion is formed into a substantially tubular shape by rolling the ends of a flat plate-shaped material so that the ends thereof are butted together, and welding at least a part of the abutting portion to form a substantially tubular shape. In the part, the conductor can be crimped from the entire circumference. Therefore, it is possible to suppress the occurrence of local stress on the conductor during crimping, and to secure the contact area between the conductor and the conductor crimped portion.

Also, a weld bead is formed by welding the abutting portion of the wire crimping portion. Since the strength of the weld bead is lower than that of other portions, the inner area of the weld bead in the butted portion on the inner surface of the conductor crimp portion is set to 20% or less of the total inner surface area of the conductor crimp portion, thereby reducing the strength of the terminal. A decrease in strength due to welding can be suppressed. In particular, such an effect is effective in the case of using a thin covered conductor wire having a cross-sectional area of 0.3 sq or less. In addition, the weld bead forms an uneven shape on the inner surface of the wire crimping portion, and such fine unevenness may cause breakage of the wire, especially during strong compression. Therefore, this effect can be reduced by reducing the area of the weld bead.

Moreover, in order to increase the tensile strength of the connecting portion, it is preferable that the thickness of the terminal is large. However, especially for small-diameter terminals, when the thickness of the terminal increases, the strength of the crimping blade tends to be insufficient. was there. Therefore, the plate thickness of the terminal is desirably 0.3 mm or less, and strong compression becomes possible by reducing the plate thickness.

In this way, since strong compression is possible, crimping conditions can be widened, and even when a terminal with a small plate thickness is used, the strength reduction due to the weld bead is suppressed, and the tensile strength of the electric wire with the terminal is increased. improvement is possible. That is, even when the plate thickness of the terminal is as thin as 0.3 mm or less, or when the compression rate of the wire crimping portion is a strong compression of 55% or less, both connection strength and connection resistance can be achieved.

Further, if the tensile strength member is made of a plurality of wire strands, unevenness is formed by the wire strands on the outer peripheral portion of the tensile strength member during compression. For this reason, even if the amount of deformation is the same, the wire can be deformed while part of the wire enters the unevenness compared to the case where the wire is deformed on the outer peripheral surface of one tensile strength member, so the wire is crushed. Excess can be suppressed.

Moreover, if the conductor wire is twisted around the outer periphery of the tensile strength member, it is possible to suppress the occurrence of loose conductor wire.

Similarly, by compressing the tip of the conductor wire from the outer peripheral side to form the terminal treated portion, it is possible to prevent the conductor wire from coming apart when the tip of the conductor wire is inserted into the tubular conductor crimping portion. can be done.

In addition, by plating the surface of the conductor wire with a conductive metal, it is effective for conductivity and tensile strength. In addition, there is also an effect of improving workability in that variations in the conductor strands are reduced during work for crimping electric wires.

In addition, by crimping so that the conductor crimping part does not come into contact with the tensile strength body, it is possible to suppress the arrangement disorder of the conductors, to ensure contact between the conductor and the conductor crimping part, and to suppress the compression of the conductor and the tension body. can be done with certainty.

A second invention is a wire harness in which a plurality of electric wires with terminals, including the electric wire with terminals according to the first invention, are integrated.

According to the second invention, it is possible to obtain a wire harness in which a plurality of small-diameter electric wires are bundled.

A third invention is a method for manufacturing the electric wire with a terminal according to the first invention, wherein the gap between the ends is 50 μm or less when the material is rolled and the ends are butted against each other. and a method of manufacturing an electric wire with a terminal, wherein the butt portions are welded.

It is desirable to reduce the gap by pressing the material from both sides before welding, maintain the position during welding, and perform welding in a state in which the material is not pushed any further.

According to the third aspect of the invention, when the butt portions are welded, the gap between the butt portions is narrowed so that the laser beam can pass through the gap to form a welding mark on the inner surface of the terminal on the opposite surface side. can be suppressed.

In addition, the material is pressed from both sides to reduce the gap, and during welding, the position is maintained and welding is performed in a state in which the material is not further pushed in, so that the gap at the butt portion can be reduced. At the same time, the weld bead is not pushed in during welding, and an increase in the area of the weld bead and the formation of irregularities can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the electric wire with a terminal etc. which can make connection strength and connection resistance compatible can be provided.

The perspective view which shows the electric wire 10 with a terminal. FIG. 2 is an axial cross-sectional view showing the electric wire with terminal 10 ; (a) is a radial cross-sectional view of the conductor crimping portion 7, which is a cross-sectional view taken along the line AA of FIG. 2, and (b) is an enlarged view of the D portion of (a). It is the elements on larger scale of the inner surface side of the conductor crimping|compression-bonding part 7, and is G arrow directional view of FIG.3(b). FIG. 4 is a diagram showing a step of forming a wire crimping portion 7; (a) and (b) are radial cross-sectional views showing the formation state of the conductor crimping portion 7, and (c) is a diagram showing a method using a pressing jig 29. FIG. The figure which shows the terminal 1 and the covered conductor 11 before crimping. (a) is a diagram showing the tip of the conductor 13, and (b) to (d) are diagrams showing the form of the terminal processing section 19. FIG. (a) to (b) are schematic diagrams showing a crimping process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view showing an electric wire 10 with a terminal, FIG. 2 is an axial cross-sectional view of the electric wire 10 with a terminal, and FIG. 3(a) is a cross-sectional view along line AA in FIG. . An electric wire 10 with a terminal is configured by electrically connecting a terminal 1 and a coated conductor 11 .

The covered conductor 11 is composed of a tensile member 17 (see FIG. 3A), a conductor 13 , and a covering portion 15 that covers the tensile member 17 and the conductor 13 . That is, the covered conductor wire 11 includes a covered portion 15 and the conductor wire 13 exposed from the tip thereof. The conducting wire 13 may be, for example, an annealed copper wire, a hard copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, or the like, but an annealed copper wire is preferable from the viewpoint of electrical conductivity.

Terminal 1 is made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. A coated conductor 11 is connected to the terminal 1 . The terminal 1 is configured by connecting a terminal main body 3 and a crimping portion 5 via a transition portion 4 .

The terminal main body 3 is formed by forming a plate-shaped material having a predetermined shape into a tubular body having a rectangular cross section. The terminal body 3 has an elastic contact piece inside which is formed by folding a plate-like material into a rectangular cylindrical body. The terminal body 3 is connected by inserting a male terminal or the like from the front end portion. In the following description, an example in which the terminal body 3 is a female terminal that allows insertion of an insertion tab (not shown) of a male terminal or the like will be shown. is not particularly limited. For example, an insertion tab for a male terminal may be provided in place of the female terminal main body 3, or a bolt fastening portion such as a round terminal may be provided.

The crimping portion 5 of the terminal 1 is a portion to be crimped with the covered conductor 11. The conductor crimping portion 7 crimps the conductor 13 exposed from the covering portion 15 to the tip side of the covered conductor 11, and the covered portion 15 of the covered conductor 11. and a covering crimping portion 9 for crimping. That is, the conductor wire 13 exposed by peeling off the covering portion 15 is crimped by the conductor crimping portion 7, and the conductor wire 13 and the terminal 1 are electrically connected. Also, the covering portion 15 of the covered conductor wire 11 is crimped by the covering crimping portion 9 of the terminal 1 .

The covering crimping portion 9 is of a so-called open barrel type. The wire crimping portion 7 is configured in a tubular shape (substantially cylindrical shape) closed in the circumferential direction. That is, the conductor crimping portion 7 is formed into a substantially tubular shape by rolling up a flat material so that the ends of the material meet, and welding at least a part of the butting portion to form a substantially tubular shape. 23 are formed. Note that the covering crimping portion 9 may also be tubular like the conductor crimping portion 7 .

As shown in FIG. 3( a ), the coated conductor 11 has a tensile strength member 17 arranged substantially in the center of the cross section, and a conductor wire 13 composed of a plurality of conductors arranged around the outer circumference of the tensile strength member 17 . The tensile strength member 17 is a member that receives tension against a tensile load. In addition, it is desirable that the tensile strength member 17 is composed of a plurality of wire strands. Further, the conductor wire 13 may be helically twisted in the longitudinal direction of the covered conductor wire 11 at the outer peripheral portion of the tensile strength member 17 .

As described above, the wire crimping portion 7 is tubular. For this reason, the conductor wire 13 can be crimped by the conductor wire crimping portion 7 from 360° around the entire circumference at a predetermined position (cross section of the predetermined position) in the axial direction of the conductor crimping portion 7 . That is, the conductor wire 13 is crimped from the entire circumference of the conductor wire 13 in the conductor crimping portion 7 . Therefore, the inner surface of the conductor crimping portion 7 is in contact with the conductor 13 over the entire circumference, and it is possible to suppress the occurrence of local stress (deformation) in the conductor 13 during crimping.

A part of the inner surface of the conductor crimping portion 7 may be provided with serrations (not shown) in the circumferential direction (direction perpendicular to the longitudinal direction). By forming the serrations in this manner, the oxide film on the surface of the conductor 13 is easily destroyed when the conductor 13 is crimped, and the contact area with the conductor 13 can be increased.

In addition, as described above, the weld bead 23 is formed in the conductor crimping portion 7 by welding the abutting portion. FIG. 3(b) is an enlarged view of part D in FIG. 3(a). The wire crimping portion 7 is welded by laser welding, for example. Here, since the weld bead 23 has a lower strength than other portions, it may cause damage to the crimped portion. In addition, the weld bead 23 has a slightly uneven shape in the circumferential direction on the inner surface side of the wire crimping portion 7 . Such an uneven shape causes breakage of the conductor wire 13 particularly when the conductor wire 13 having a small diameter and the conductor wire crimping portion 7 are strongly crimped.

For this reason, it is desirable that the area of the weld bead 23 of the butted portion on the inner surface of the conductor crimping portion 7 is 20% or less of the total inner surface area of the conductor crimping portion 7 . FIG. 4 is a view in the direction of arrow G in FIG.

Here, as shown in FIG. 2, assuming that the total length of the wire crimping portion 7 in the longitudinal direction of the terminal is C, in the vicinity of both ends in the longitudinal direction, in order to avoid sudden deformation, the amount of compression is intentionally increased toward the ends. It may be tapered to make it smaller. In this case, the length (B in the drawing) that is actually crimped with a predetermined compression rate is the crimped length of the conductor crimping portion 7 .

That is, the area S1 of the weld bead 23 of the butted portion on the inner surface of the wire crimping portion 7 is calculated by length B×width (average width) H in FIG. Further, the total inner surface area S2 of the conductor crimping portion 7 is calculated by length B×diameter E (FIG. 3(a))×π. In this case, it is desirable that S1/S2(%)≦20%. By doing so, the influence of the weld bead 23 can be reduced.

Moreover, it is desirable that the height of the unevenness of the welding bead 23 at the butted portion on the inner surface of the wire crimping portion 7 is less than 50 μm. Here, as shown in FIG. 3B, the uneven height of the weld bead 23 is the maximum protrusion height to the inner surface side when the extension line of the part other than the weld bead 23 is used as a reference in the crimping range. (F in the figure). By doing so, the influence of the weld bead 23 can be reduced more reliably.

Here, this embodiment is particularly effective when the cross-sectional area of the conducting wire 13 (total cross-sectional area of the wires) is 0.3 sq or less. As described above, when a large-diameter coated conductor is used for connection to a crimp terminal, it is easy to perform crimping at the conductor crimping portion at a compression ratio that achieves both connection strength and connection resistance. When the diameter is small, it is difficult to control the balance between conductivity and tensile strength only by compressibility. For example, if a small-diameter coated conductor is compressed at a low rate (strongly compressed), the conductor may break. In contrast, the present embodiment is particularly effective in preventing the wire from being pulled out (disconnection prevention) when the wire is crimped under the condition that the compression rate is 55% or less.

Since the conducting wire 13 is used together with the tensile member 17, the cross-sectional area of the conducting wire 13 may be 0.05 sq or less. The smaller the cross-sectional area of the conducting wire 13, the greater the effect of this embodiment. From the viewpoint of securing crimping strength, the cross-sectional area of the conductor 13 is preferably 0.01 sq or more, more preferably 0.03 sq or more.

The tensile strength member 17 may be a metal wire such as a steel wire, or may be made of resin or fiber-reinforced resin, but is configured by bundling a plurality of strands. For example, PBO (polyparaphenylene-benzobis-oxazole) fiber, aramid fiber, carbon steel wire, stainless steel wire, liquid crystal polyester fiber, etc., can be applied as the wire constituting the tensile member 17, but corrosion resistance is taken into consideration. Then, it is desirable to be a non-metallic wire.

Moreover, it is desirable that the tensile strength of the tensile strength member 17 is higher than the tensile strength of the conducting wire 13 . Note that the tensile strength means the maximum stress at which a material breaks when subjected to tensile stress, but in the present embodiment, it is used as a relative indicator of the ease of breaking due to crushing of the material during crimping. That is, the tensile strength member 17 is made of a material that is less deformable than the conductive wire 13 during crimping. Furthermore, the Young's modulus of the tensile member 17 is preferably higher than the Young's modulus of the conductor 13, and the yield stress (or yield strength) of the tensile member 17 is higher than the yield stress (or yield strength) of the conductor 13. desirable.

Next, a method for manufacturing the electric wire with terminal 10 will be described. FIG. 5 is a perspective view showing a step of forming the wire crimping portion 7 of the terminal 1 before crimping. As described above, the terminal 1 has the terminal main body 3 and the crimping portion 5 , and the crimping portion 5 is composed of the conductor crimping portion 7 and the cover crimping portion 9 . The conductive wire crimping portion 7 is joined by rolling a plate-shaped material, butting the ends thereof, and welding the butted portions in the longitudinal direction by, for example, a laser 27 .

FIG. 6(a) is a cross-sectional view when welding the butt portion 25. FIG. Generally, when a plate-shaped material is rolled into a tubular shape using a mold or the like, a gap is formed in the abutting portion 25 due to springback.

FIG. 6(b) is a cross-sectional view of the conductor crimping portion 7 after welding when laser welding is performed in this state. As described above, a weld bead 23 is formed at the butted portion. At this time, it is desirable that the area of the weld bead 23 on the inner surface of the butted portion of the terminal is 20% or less of the inner area of the terminal. For this reason, laser welding is desirable because the bead width can be varied.

Here, if welding is performed in a state in which a gap of a predetermined size or more is left in the butted portion 25 before welding, part of the laser 27 is transmitted through this gap. Therefore, when the butt portion 25 is laser-welded, the laser beam 27 that has passed through the gap of the butt portion 25 forms an opposing surface welding mark 23a on the inner surface of the conductor crimping portion 7 on the opposite surface side of the butt portion 25 . As with the weld bead 23, the welding mark 23a on the facing surface not only causes a decrease in strength, but also forms a fine uneven shape on the inner surface of the wire crimping portion 7, which causes disconnection of the wire 13 during crimping. is not desirable.

Therefore, it is desirable that the gap between the butted portions 25 during welding is 50 μm or less. That is, when the material is rolled and the ends are butted against each other, the butt part 25 is welded so that the gap between the ends is 50 μm or less (more preferably 10 μm or less). The formation of 23a can be suppressed.

In this way, as a method for controlling the gap of the butted portion 25, it is desirable to perform welding in a state in which both sides of the lead wire crimping portion 7 before welding are pressed by pressing jigs 29, as shown in FIG. 6(c). . For example, after the conductor crimped portion is rounded by a die, the material is pressed from both sides by the pressing jig 29 before welding to reduce the gap formed by the pullback. By doing so, the gap between the butted portions 25 can be set to a predetermined value or less.

Here, during welding, it is desirable to perform welding in a state in which the holding jig 29 maintains its position and does not push the material any further. That is, it is desirable to perform welding in a state in which no force is applied to the end face of the butted portion 25 at the time of welding. If the gap between the butted portions 25 is eliminated and welding is performed in a state of being pressed from both sides, when the metal is softened by welding, the butted portions 25 are slightly pushed in, which causes an increase in the weld bead 23 and an increase in the inner surface of the wire crimping portion 7. It becomes a factor of formation of unevenness.

For this reason, after the lead wire crimping portion 7 before welding is pressed from both sides by a predetermined amount to reduce the gap, the material is supported only by the force against the springback of the material, and no force is applied to the end faces of the butted portions 25. It is desirable to avoid For example, the gap between the ends is not 0 mm, but a gap of more than 0 mm may be provided so that the two are not in contact with each other.

Next, as shown in FIG. 7 , the covering portion 15 at the tip of the covered conductor 11 is peeled off to expose the conductor 13 at the tip, which is then inserted into the crimping portion 5 . Before inserting into the crimping portion 5 of the terminal 1, the leading end portion of the conducting wire 13 may be subjected to terminal treatment.

FIG. 8(a) is a diagram showing a state in which a terminal processing portion 19 is formed at the tip of the conductor 13. FIG. The terminal processing unit 19 is a processing unit that integrates each strand of the conducting wire 13 so as not to come apart.

As described above, the tensile strength member 17 is arranged substantially in the center, and the conducting wire 13 is arranged around it. Conductor 13 consists of a plurality of conductors. In such a case, as shown in FIG. 8(b), the terminal treated portion 19 can be formed by compressing at least the tip portion of the conductor 13 from the outer peripheral side. By compressing the tip portion of the conductor wire 13 from the outer peripheral side in this manner, the wires are prevented from coming loose, and the insertion into the tubular crimping portion 5 is facilitated.

Alternatively, as shown in FIG. 8(c), at least the leading end portion of the lead wire 13 may be plated collectively to form the terminal treated portion 19 with the plating layer 21. FIG. In this way, the leading ends of the conductor wires 13 are plated all at once from the outer periphery, so that the wires are prevented from coming apart, and insertion into the tubular crimping portion 5 is facilitated.

It should be noted that, depending on the plating method, the temperature may be high when plating is performed collectively from the outer circumference of the conductor wire 13 . If batch plating is performed by such a plating method after the conductors 13 have been twisted, the tensile strength member 17 may deteriorate due to heat and the tensile strength may decrease.

In such a case, as shown in FIG. 8(d), the plating layer 21 may be formed for each conductor and then twisted around the outer circumference of the tensile strength member 17. Then, as shown in FIG. Alternatively, the plating layer 21 may be formed for each conductor, and the tip portions of the plurality of conductors may be collectively plated from the outer periphery. In this case, the type of plating for each conductor and the type of batch plating may be changed. As mentioned above, by performing batch plating, it is possible to suppress the scattering of the conductors, but if the conductors are bundled and plated all at once, they may be partially There is a possibility that thick and thin portions of the plating may occur. On the other hand, by performing a base plating treatment for each conductor in advance, this effect can be reduced and substantially uniform batch plating can be performed.

It should be noted that the terminal treatment portion 19 is not limited to the method using compression or plating treatment, and for example, the ends of the conductor wires 13 may be subjected to soldering treatment or welding treatment to suppress the unraveling of the wires. In addition, a plurality of terminal treatments such as compression from the outer circumference and batch plating may be used together.

Next, the covered conductor 11 whose tip is treated in this manner is inserted from the rear end side of the tubular crimping portion 5 of the terminal 1 . When the tip of the covered conductor wire 11 is inserted into the crimping portion 5 , the exposed portion of the conductor wire 13 is positioned inside the conductor crimping portion 7 , and the covered portion 15 is positioned inside the covering crimping portion 9 . At this time, the tip of the conductor wire 13 may protrude from the tip of the conductor crimping portion 7 .

Fig. 9(a) is a sectional view showing an upper blade die 31a, a lower blade die 31b, etc. before crimping of the terminal crimping blade dies for manufacturing the electric wire 10 with a terminal, and Fig. 9(b) is a crimping during crimping. 5 is a cross-sectional view showing a portion 5; FIG. The upper die 31a and the lower die 31b have a substantially semi-cylindrical cavity extending in the longitudinal direction. The upper blade 31a includes a coated crimping blade 34 corresponding to the coated crimping portion 9 and having a diameter slightly smaller than the radius of the coated crimping portion 9, and a coated crimping blade 34 corresponding to the conductor crimping portion 7. A wire crimping blade die 32 having a small diameter is also provided. That is, the upper blade 31a and the lower blade 31b are formed so that both portions corresponding to the wire crimping portion 7 and the cover crimping portion 9 have a substantially circular cross section when the terminal 1 is crimped.

As shown in FIG. 9(b), when the upper blade 31a and the lower blade 31b are engaged with each other to compress the crimping portion 5, the conductor crimping portion 7 is crimped to the conductor 13, and the covering crimping portion 9 becomes the covering portion. 15 is crimped. In the cross section of the conductor crimping portion 7 in the longitudinal direction, the conductor crimping blade 32 has a straight portion at substantially the center in the longitudinal direction, and both ends are tapered. That is, the conductor crimping portion 7 is compressed at a substantially constant compression rate in the vicinity of the central portion in the longitudinal direction, and is formed such that the amount of compression gradually decreases at both ends. In this case, with respect to the length C of the conductor crimping portion 7, the crimping portion length B of the conductor crimping portion 7 is the length of the cross-sectional linear portion that is compressed at a constant compression ratio.

The electric wire 10 with a terminal can be obtained by the above. Furthermore, it is possible to obtain a wire harness in which a plurality of electric wires with terminals are integrated, including the obtained electric wire with terminals 10 .

Here, it is desirable that the compressibility of the wire crimping portion is 55% or less. Even if the compressibility is set to 55% or less, the uneven shape of the weld bead 23 is less likely to affect the tensile strength, and the crimp resistance between the terminal and the wire can be reduced. Regarding the compression rate of the conductor crimping portion, the total cross-sectional area of the conductor 13 before the crimping step is A0, and the total cross-sectional area of the conductor 13 in the conductor crimping portion 7 after being compressed by the upper blade 31a and the lower blade 31b. is A1, the compressibility of the wire crimping portion 7 is A1/A0 (%).

Since the tensile strength member 17 has a higher strength than the conductor wire 13 and is less likely to deform, the cross-sectional area of the tensile strength member 17 does not decrease significantly when compressed, and deformation (reduction in cross-sectional area) of the conductor wire 13 mainly progresses. . Here, as described above, the conductor wire 13 is crimped from the entire circumferential direction of the conductor wire 13 in the conductor crimping portion 7 . Moreover, since the tensile strength member 17 is formed of a plurality of tensile strength member wires, unevenness is formed in the outer peripheral portion of the tensile strength member 17 (region). Therefore, at the interface between the tensile strength member 17 and the conductor wire 13, the conductor wire 13 is deformed according to the unevenness of the tensile strength member wire. Since the outer shape of the tensile strength member 17 becomes uneven, the contact area between the conductor 13 and the tensile strength member 17 increases, and the frictional force increases. For this reason, it becomes easy for the force to be transmitted from the conductor 13 to the tensile strength member 17 in response to tension, and an increase in strength can be expected when the tension is applied to the conductor 13 .

For example, if the tensile member 17 is a single wire, the interface between the tensile member 17 and the conducting wire 13 will be substantially smooth. At this time, since the tensile member 17 is difficult to deform relative to the conductor 13 , the conductor 13 is deformed so as to be crushed along the surface of the tensile member 17 . As a result, the conducting wire 13 may become too thin and break. On the other hand, if unevenness is formed on the outer peripheral surface of the tensile member 17, the conductor wire 13 can be deformed so as to fit into the unevenness, so that it is not excessively crushed and wire breakage can be suppressed.

Since the tensile strength member 17 is less deformed than the conductor wire 13, it is less likely to break due to a reduction in cross-sectional area. In particular, since the conductor crimping portion 7 is tubular, the conductor 13 is compressed from the entire circumference, the conductor 13 is arranged between the tensile strength member 17 and the conductor crimping portion 7, and the tensile strength member 17 and the conductor crimping portion 7 do not contact each other. Therefore, the tensile strength member 17 is not damaged.

It should be noted that, during compression, a portion of the wire constituting the tensile member 17 may enter between the conductors 13 and a portion of the tensile member 17 may come into contact with the conductor crimping portion 7 . In order to secure the conduction area between the conductor 13 and the conductor crimping portion 7, it is desirable that the tensile member 17 and the conductor crimping portion 7 do not come into contact with each other. good.

Here, in general, especially for small-diameter terminals, when the plate thickness of the terminal increases, the strength of the crimping blade becomes insufficient. There is For this reason, when the plate thickness is increased, it is necessary to perform crimping under conditions of a high compression rate (conditions of less compression). Therefore, considering crimpability, it is desirable that the plate thickness of the terminal is 0.3 mm or less. By doing so, it is possible to further reduce the compression rate, and it is possible to suppress the disconnection of the electric wire and the increase in electrical resistance.

As described above, according to the present embodiment, the conductor wire 13 is crimped in the conductor crimping portion 7 from all 360° directions, so that local stress (deformation) is generated in the conductor wire 13 during crimping. can be suppressed. In addition, crimping can be performed without greatly destroying the structure of the tensile strength member 17 in the center and the conductive wire 13 twisted around it. Moreover, since the conductor crimping portion 7 is in contact with the entire circumference of the conductor 13, deterioration of resistance can be suppressed.

In addition, since the inner area of the weld bead 23 is 20% or less of the total inner surface area of the wire crimping portion 7, the influence of the uneven shape on the inner surface side of the weld bead 23 and the influence of the strength reduction of the terminal due to the weld bead 23 are eliminated. can be made smaller. Therefore, it is possible to achieve both tensile strength and connection resistance even in a condition where compression is particularly strong (compression rate of 55 or less).

Such an effect is particularly effective for a thin electric wire of 0.3 sq or less, for which it is difficult to achieve both low connection resistance and high tensile strength only by compressibility.

In addition, by optimizing the gap of the butt portion 25 during welding, it is possible to reduce the height of the irregularities on the inner surface of the weld bead 23 and to suppress the formation of the welding mark 23a on the opposing surface. .

Various electric wires with terminals were produced, and the electrical properties (crimped part resistance performance) and mechanical properties (tensile strength performance) of the crimped part were evaluated. As the terminal, a tubular terminal (see FIG. 7) having a wire crimping portion was used. The inner diameter of the conductor crimped portion was 0.45 mm, and the crimped length of the conductor crimped portion (B in FIG. 9B) was 4 mm.

As the coated conductor wires, those in which a tensile strength member was arranged in the center of the cross section and the conductor wires were twisted together on the outer periphery and tin-plated (see FIG. 8(d)) were used. The cross-sectional area of the conductor wire, which is the total cross-sectional area of the conductors, was 0.05 sq. Annealed copper wire and PBO fiber were used as the conductor material. The tensile strength of the annealed copper wire is 234 MPa, and the tensile strength of the tensile member is 4400 MPa.

The electrical properties were evaluated by measuring the electrical resistance between the terminal and the coated conductor. As for the mechanical properties, the tensile strength was measured by pulling the covered conductor from the terminal and measuring the load when the covered conductor was pulled out. Each condition and results are shown in Tables 1 and 2.

In the table, the "butt part gap" is the gap when the lead wire crimped part is laser-welded into a tubular shape. The clearance between the butted portions was set to a predetermined clearance using a microvise. The presence or absence of welding marks on the opposing surface is the presence or absence of welding marks on the opposing surface of the weld bead when the laser is transmitted through the gap during welding. Calculated by In addition, when the area ratio of the welding traces on the opposing surface was less than 1%, it was judged that there were no welding traces on the opposing surface.

The crimping portion resistance value is the electrical resistance between the tip of the terminal and the rear end of the 100 mm long covered conductor. A crimping portion resistance value of less than 1 mΩ was evaluated as “○”, 1 mΩ to 2 mΩ was evaluated as “Δ”, and over 2 mΩ was evaluated as “×”. Tensile strength is the load applied when the coated conductor is pulled out from the terminal. As for the tensile strength performance, 50N or more was evaluated as "○", and less than 50N as "X".

As can be seen from Tables 1 and 2, in Examples 1 to 6 in which the weld bead inner area/total inner area is 20% or less, the compression ratio is all 55 or less. Both performance and tensile strength performance were acceptable.

On the other hand, in Comparative Examples 1 to 3, the weld bead internal area/total internal area exceeded 20%, the terminal was confirmed to be damaged, and the tensile strength performance was unsatisfactory. Further, in Comparative Example 2, since welding traces on the opposing surfaces were more generated than in Comparative Example 1, the tensile strength was further lowered. Moreover, since the compressibility of Comparative Example 3 was high, both the crimped portion resistance performance and the tensile strength performance were unsatisfactory.

Although details are omitted, in each of the above-described examples, welding was performed using a micro vise while maintaining a predetermined gap between the butted portions. If welding is performed while pressing from both sides of the butt joint, when the strength of the welded joint drops momentarily, the welded joint will shift due to the maintained pressing force, resulting in an overlapping shape, which may result in poor welding. there were. In addition, the inner diameter of the welded portion became small, making it difficult to insert an extra-fine wire. For this reason, it is desirable to perform welding so that the butted portions do not come into contact and are pressed.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not influenced by the above-described embodiments. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. be understood to belong to

For example, in the above description, an example in which one layer of the conductor 13 is arranged around the outer circumference of the tensile strength member 17 was shown, but the arrangement of the conductor 13 is not limited to this. If the conductor wire 13 is arranged on the outer peripheral side of the tensile member 17, the conductor wire 13 may be arranged in two layers around the tensile member 17, or the conductor wire 13 may be arranged in three layers around the tensile member 17. good.

In the above description, the tensile strength member 17 is made up of a plurality of tensile strength element wires. A single wire may be used as long as an uneven shape is formed on the outer peripheral portion.

Reference Signs List 1 Terminal 3 Terminal main body 4 Transition portion 5 Crimping portion 7 Wire crimping portion 9 Insulated crimping portion 10 Electric wire with terminal 11 Insulated conductor 13 ...... Conducting wire 15 Covered portion 17 Tensile member 19 Terminal treated portion 21 Plating layer 23 Weld bead 23 a Welded mark on opposite surface 25 Butt portion 27 …… Laser 29 …… Holding jig 31 a …… Upper blade mold 31 b …… Lower blade mold 32 …… Wire crimping blade mold 34 …… Coated crimping blade mold

Claims (11)

An electric wire with a terminal in which a coated conductor and a terminal are electrically connected,
The coated conductive wire has a tensile strength body, a conductive wire, and a coating portion that coats the tensile strength body and the conductive wire,
The conductor has a cross-sectional area of 0.3 sq or less,
The terminal comprises a conductor crimping part to which the conductor exposed from the covering part at the tip of the covered conductor is crimped, and a covered crimping part to which the covering part of the covered conductor is crimped,
The conductor crimping portion is formed into a substantially tubular shape by rolling the ends of a flat plate-shaped material so that they abut and welding at least a part of the butting portion, and welding the butting portion on the inner surface of the conductor crimping portion. The area of the bead is 20% or less of the total inner surface area of the wire crimping portion,
An electric wire with a terminal, wherein the conducting wire is crimped from the entire circumferential direction of the conducting wire in the conducting wire crimping portion. 2. The electric wire with a terminal according to claim 1, wherein the plate thickness of the terminal is 0.3 mm or less. 3. The electric wire with a terminal according to claim 1, wherein the compressibility of said conductor crimping portion is 55% or less. The electric wire with a terminal according to any one of claims 1 to 3, wherein the tensile strength member comprises a plurality of wire strands. The electric wire with a terminal according to any one of claims 1 to 4, wherein the conducting wire is twisted around the outer circumference of the tensile strength member. The electric wire with a terminal according to any one of claims 1 to 5, wherein at least a tip portion of the conducting wire is compressed from an outer peripheral side. The electric wire with a terminal according to any one of claims 1 to 6, wherein the conducting wire is plated. The electric wire with a terminal according to any one of claims 1 to 7, wherein the conductor crimping portion does not come into contact with the tensile strength member. A wire harness in which a plurality of electric wires with terminals including the electric wire with terminals according to any one of claims 1 to 8 are integrated. A method for manufacturing the terminal-equipped electric wire according to any one of claims 1 to 8,
A method for manufacturing an electric wire with a terminal, characterized in that when a raw material is rolled and the ends are butted together, the butted portions are welded so that the gap between the ends is 50 μm or less. 11. The production of the electric wire with a terminal according to claim 10, wherein the material is pressed from both sides to reduce the gap before welding, and welding is performed in a state in which the material is kept in that position and the material is not further pushed in during welding. Method.

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